1. Field of the Invention
This invention relates to electrophotocopy machines and, in particular, to a drive system for a reciprocating carriage that is mounted on such a machine.
Electrophotocopy machines are well known devices that are used for reproducing all forms of documents. These machines are usually either of the plain paper type or the coated paper type. The plain paper machines have a reuseable photoconductor and produce a copy on bond paper. The coated paper machines use a special paper that has been treated with a photosensitive substance so that the copy sheet functions as the photoconductor. These machines include a number of processing stations. At one station, the photoconductor is uniformly electrostatically charged. At another, the document to be copied is illuminated. At an imaging station the charged photoconductor is exposed to an image of the illuminated document to selectively discharge light struck areas of the photoconductor thereby forming a latent electrostatic image thereon. At a developing station, the latent image is developed by applying either a wet or dry type developer. In plain paper copiers, the developed image is thereafter transferred to a plain paper copy sheet. Finally, the toner is fixed to the copy sheet in one of a number of well known ways in order to yield a finished copy.
It is readily apparent from the foregoing description that the exposing and imaging stations perform an important function in copying machines because they provide the nexus between the document and the photoconductor. There are a number of configurations and combination of such stations. One kind of machine includes a sheet handling and feeding apparatus for moving an original document across a fixed, transparent illumination slit. Such machines, however, cannot handle bulky documents such as books. Another kind of machine uses a stationary, flat glass platen on which a book or single folio document is illuminated by a flash lamp. A lens focuses the flashed image onto a substantially flat photoconductor. Other stationary platen machines scan expose the photoconductor to the document by means of a movable mirror, lens and lamp arrangement. Still other machines use a fixed lens, mirror and lamp arrangement combined with a movable carriage that carries a document face down on a transparent platen across an illuminating station. The carriage and the photoconductor move in synchronism past the respective exposure and imaging stations. The reciprocating carriage kind of machine is favored for its relative simplicity of manufacture, ease of operation and compactness of size.
2. Description of the Prior Art
The prior art includes a number of machines that use a reciprocating document carriage. In U.S. Pat. No. 3,697,165 a carriage is linked with a lost motion coupling to a drive chain that is mounted on sprockets positioned adjacent to the carriage transfer and home positions. As the carriage link begins to pass around the underside of the sprocket, the link actuates a reversing switch effective to shift a transmission to drive the carriage in the opposite direction. Other chain loop and link drive mechanisms are found in U.S. Pat. Nos. 3,779,114 and 3,424,526. Still other drive mechanisms include a pair of racks mounted on a carriage and oppositely driven pinions alternately movable into and out of engagement with the racks, a pulley and belt arrangement with the belt driven in sequentially opposite directions by the alternate actuation of two oppositely driven electromagnetic clutches, and a pulley, clutch, spring return mechanism where the carriage is driven in one direction and a reset spring is tensioned to return the carriage to its initial position. Examples of the foregoing drives can be found in U.S. Pat. Nos. 3,424,526, 3,804,512 and 3,734,604. These prior art mechanisms suffer from one or more defects, including multiple electromagnetic clutches, high mechanical stresses on driving elements during reversal of carriage travel direction and complex electromechanical actuating circuits and apparatus.
Therefore, it is an object of this invention to provide a simple drive mechanism for a reciprocating carriage of an electrophotocopy machine.
It is another object to provide a drive mechanism normally engaged with the carriage for driving the carriage in one direction.
A further object is to provide an electrophotocopy machine having improved book copying capabilities.
Still another object is to provide an electrophotocopy machine wherein the carriage is capable of being translated through its non-copying stroke at a more rapid rate than its copying stroke.
Yet another object is to provide an electrophotocopy machine having improved drive means for reciprocating an original document carriage.
A further object is to provide a copy sheet supply apparatus that prevents the feeding of copy sheet slivers.
Another object is to provide an apparatus for actuating a copy paper feed means in response to the position of the carriage.
It is also an object to provide a control system having a common actuating means for actuating the illuminating station, controlling the direction of travel of the carriage and the operation of a severing means for cutting copy sheets from a web of copy paper.
An additional object is to provide an electrophotocopy machine which is simple in design, inexpensive to manufacture, efficient and reliable in operation.
It is another object to drive the carriage to a home position as soon as the machine is energized.
These and other objects of the invention will become apparent hereinafter.